I dunno, I don't think that would really happen. I'm always trying to type the same word (I don't say "pish" in my head, after all, I think "push"), so it doesn't seem to be a random walk away from correctness, just some wavering around it. And it's not like I have that many commands I need to type commonly enough to make an alias for-- maybe a couple dozen? And for most of them, I don't make typos so I don't feel the need to make an alias.